The invention relates to an arrangement for generating a plasma by means of cathode sputtering according to the preamble of patent claim 1.
In numerous fields of technology it is required to apply thin layers on substrates. For example, glass panes are coated in order to lend to them special properties or watch cases comprising a less noble material are coated with a layer comprising a noble material.
For the application of thin layers on substrate numerous processes have already been suggested of which only the electroplating technique and the coating out of a plasma will be mentioned. The coating out of the plasma has increasingly gained in importance during the past years because it permits a multiplicity of materials as coating material.
In order to generate a plasma suitable for coating, also various processes have been suggested. Of these processes the cathode sputtering process is of great interest due to its high coating rates.
In a known arrangement for the generation of a plasma of high density a high-frequency generator is used which transmits 13.56 MHz waves along a magnetic field which arrives through an external magnetic field generator into the discharge volume (U.S. Pat. No. 4,990,229). With the aid of this arrangement helicon whistler waves are excited in a plasma volume which lead to a particularly high plasma activation. In order to excite particular wave modes for whistler waves, special antenna structures are provided. An antenna for the excitation of whistler waves at an excitation frequency of 13.56 MHz is layed out so that it excites the m=0 and m=1 modes.
The disadvantage of the known arrangement resides therein that with it indeed a highly activated and high ionized plasma can be generated, however, that it is not possible to carry out a sputter coating.
Furthermore, a sputter installation is known which comprises a high-frequency excitation coil with four windings, which is disposed between a disk-form target and a substrate holder in a conventional DC diode installation (Matsuo Yamashita: "Effect of magnetic field on plasma characteristics of built-in high-frequency coil type sputtering apparatus", J. Vac. Sci. Technol. A 7 (4), July/August 1989, p. 2752-2757). Perpendicularly to the axis of the high-frequency excitation coil extends in addition a static magnetic field which penetrates into the plasma region. With this sputter installation it is however not possible to generate whistler waves.